Red light emission from europium doped zinc sodium bismuth borate glasses

Zinc sodium bismuth borate (ZNBB) glasses doped with different concentrations of europium were prepared by conventional melt quenching method and characterized through the measurements of density, refractive index, X-ray diffraction (XRD), Fourier Transform Infrared (FTIR) spectra, optical absorption, luminescence and radiative lifetimes. FTIR spectra showed seven characteristic peaks of bismuth and borate functional groups in the range of 400–1600 cm⁻¹. The optical band gap and bonding parameters have been calculated from absorption spectra. Photoluminescence spectra recorded in the visible region with 394 nm excitation are used to calculate the Judd-Ofelt (JO) intensity parameters (Ω₂ and Ω₄). The JO intensity parameters have been used to calculate the radiative parameters such as branching ratio (β), stimulated emission cross-section (σ_se), transition probability (A) for the fluorescent level of ⁵D₀→⁷F₂. Decay rates through single exponential are used to calculate the lifetime (τ_m) of the meta-stable state ⁵D₀ of (Eu³⁺ ion) these glasses. The radiative parameters measured for all these glasses show 0.7 mol% europium doped zinc sodium bismuth borate glass ⁵D₀→⁷F₂ transition has the potential for red laser applications. The quality of the colour emitted by the present glasses are estimated quantitatively by CIE chromaticity coordinates, which confirms the suitability of these glasses as a red emitting material for field emission technologies and LEDs.